Question on side-mouth assembly


First post and submission, have run into a bit of a road block and unsure where to go since i have found little on the topic of mouths attached from a side angle. Was inspired by this pony rig from (My Pony) and trying to do something similar in construction though i cannot for the life of me figure how to construct this.

I assume the neck is auto patched to the head region, then the mouth would be under the head while patching over the nose/head area?

If anyone has a lead or some guidance on how to pull this off would be great help, never done something like this before!

Thanks again!